Lithium heptadecafluorooctanesulfonate catalyzed Mannich-type and aza-Diels-Alder reactions in supercritical carbon dioxide

Article abstract of DOI:10.1016/j.tet.2004.05.065

The Mannich-type reaction of imines with (1-methoxy-2-methylpropenyloxy) trimethylsilane and aza-Diels-Alder reaction of imines with Danishefsky's diene can be carried out in scCO₂ in the presence of lithium heptadecafluorooctanesulfonate which

Full text of DOI:10.1016/j.tet.2004.05.065

Tetrahedron 60 (2004) 6163–6167
Lithium heptadecafluorooctanesulfonate catalyzed Mannich-type
and aza-Diels–Alder reactions in supercritical carbon dioxide
*
Min Shi, Shi-Cong Cui and Qing-Jiang Li
State key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu,
Shanghai 200032, China
Received 17 November 2003; revised 31 March 2004; accepted 14 May 2004
Available online 11 June 2004
Abstract—The Mannich-type reaction of imines with (1-methoxy-2-methylpropenyloxy)trimethylsilane and aza-Diels–Alder reaction of
imines with Danishefsky’s diene can be carried out in scCO2 in the presence of lithium heptadecafluorooctanesulfonate which offer a way to
synthesize b-amino carbonyl compounds and nitrogen-containing six-membered ring compounds under environmentally benign conditions.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
Danishefsky’s diene with imines in water under neutral
conditions.22 In order to explore an alternative environ-
mentally benign condition for these two reactions, we
attempted to carry out these reactions in scCO2 in the
presence of alkaline salt or other metal catalysts. Herein, we
wish to report the lithium heptadecafluorooctanesulfonate-
catalyzed Mannich-type and aza-Diels–Alder reactions of
imines in scCO2 under mild conditions.
Green chemistry provides challenges and opportunities to
those who practice chemistry in industry and academic
research.1–5 Of those suitable alternatives to conventional
solvents ionic liquids,6 perfluorinated hydrocarbons,7
water,8 and supercritical carbon dioxide (scCO2)9–11 have
been widely investigated. Several advantages which include
inexpensiveness, non-flammability, its environmentally
benign nature and its ready separability from products
make scCO2 an attractive solvent for organic reactions.
Above the critical temperature and pressure, (Tc¼31 8C,
Pc¼7.4 MPa) CO2 has gas-like viscosity and liquid-like
density. These moderate critical conditions allow for safe
commercial and laboratory operating conditions. Indeed, a
great variety of metal-catalyzed reactions have been carried
out in scCO2.10–19
2. Results and discussion
We initially chose various alkali metal salts as catalyst
(10 mol%) to promote Mannich-type reaction of benzyl-
idene(phenyl)amine 1a (0.30 mmol, 54 mg) with (1-meth-
oxy-2-methylpropenyloxy)trimethylsilane (0.45 mmol,
90 mL) at 50 8C and under 10 MPa in scCO2. The results
are listed in Table 1. The reaction proceeded smoothly to
give desired adduct 2a in moderate to high yields in the
presence of alkali metal salts such as LiOTf (CF3SO3Li),
LiOPf (C8F17SO3Li), NaOTf (CF3SO3Na), NaOPf
(C8F17SO3Na) and KOPf (C8F17SO3K) (Table 1, entries
1–4 and 6). On the other hand, KOTf (CF3SO3K), CsOTf
(CF3SO3Cs) and CsOPf (C8F17SO3Cs) performed poorly
(Table 1, entries 5, 7 and 8). The best result was obtained
with LiOTf (Table 1, entry 2). In general alkali metal salts
derived from a long chain perfluorinated sulfonic acid
severed as effective promoters for this Mannich-type
reaction in scCO2. This is because a long perfluorinated
alkyl chain can allow the scCO2 reaction system become an
effective homogenous phase, namely, this catalyst is soluble
in scCO2. Through the high pressure glass window placed in
scCO2 reaction vessel, we confirmed that the LiOPf
(C8F17SO3Li), 1a and (1-methoxy-2-methylpropenyloxy)-
Mannich-type and aza-Diels–Alder reactions are useful
synthetic methods to prepare various b-amino carbonyl
compounds20 and nitrogen-containing six-membered ring
compounds,21 which constitute a broad spectrum of natural
products, biologically active compounds, and other func-
tional materials. Recently, Kobayashi and co-workers have
developed Mannich-type reactions in water using a
hydrophobic polymer-supported sulfonic acid catalyst and
alkaline salt-catalyzed aza-Diels–Alder reactions of
Keywords: Mannich-type reaction; Aza-Diels–Alder reaction; Imines; (1-
Methoxy-2-methylpropenyloxy)trimethylsilane; Danishefsky’s diene;
Supercritical carbon dioxide; Lithium heptadecafluorooctanesulfonate;
Environmentally benign conditions.
*
Corresponding author. Tel.: þ86-21-64163300x342; fax: 86-21-
64166128; e-mail address: mshi@pub.sioc.ac.cn
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.05.065

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M. Shi et al. / Tetrahedron 60 (2004) 6163–6167
Table 1. The alkali metal salt catalyzed-Mannich-type reaction in scCO2
Entry
Catalyst
Time (h)
2a, Yields (%)a
1
2
3
4
5
6
7
8
LiOTf
LiOPf
NaOTf
NaOPf
KOTf
KOPf
10
10
10
10
10
10
10
10
59
93
54
88
6
83
Trace
21
CsOTf
CsOPf
LiOPf¼C8F17SO3Li.
a
Isolated yield.
Table 2. LiOPf catalyzed-Mannich-type reaction in scCO2
Entry
Ar
C6H5
p-MeOC6H4
p-NO2C6H4
p-ClC6H4
C6H5
Ar0
Time (h)
2, Yields (%)a
1
2
3
4
5
m-CF3C6H4
C6H5
C6H5
C6H5
m-FC6H4
10
10
10
10
10
2b, 85
2c, 66
2d, 83
2e, 60
2f, 52
a
Isolated yield.
Table 3. Alkali and lanthanide metal salts catalyzed-aza-Diels–Alder reaction in scCO2
Entry
Catalyst
Time (h)
3a, Yields (%)a
b
1
2
3
4
5
6
7
8
—
LiOTf
LiOPf
NaOPf
KOPf
Sc(OTf)3
Yb(OTf)3
Yb(OPf)3
10
10
10
10
10
10
10
10
—
80
88
78
32
64
40
45
a
Isolated yield.
No reaction.
b
trimethylsilane are completely dissolved in scCO2 to form a
homogeneous reaction system.
Turning our attention to aza-Diels–Alder reactions in
scCO2 we noted the reaction of Danishefsky’s diene with
imines had been conducted previously in methanol, ethanol,
DMF, and THF in the absence of any catalyst.23 Thus, we
first examined the aza-Diels–Alder reaction of
Danishefsky’s diene (0.45 mmol, 77.4 mg) with benzyl-
idene(phenyl)amine 1a (0.3 mmol, 54 mg) in the absence of
any catalyst and found no reaction occurred in scCO2
(Table 3, entry 1). We believe that this is because scCO2 is a
non-polar solvent similar to alkanes which are ineffective to
Under the optimized reaction conditions, we then examined
this Mannich-type reaction of various imines with
(1-methoxy-2-methylpropenyloxy)trimethylsilane in the
presence of LiOPf (10 mol%) in scCO2. The results are
summarized in Table 2. As can be seen from Table 2, the
desired adducts 2 can be obtained in good yields (Table 2,
entries 1–5).

M. Shi et al. / Tetrahedron 60 (2004) 6163–6167
6165
promote aza-Diels–Alder reaction of Danishefsky’s diene
with imines in contrast to polar organic solvents. However,
we found that using LiOTf, LiOPf, or NaOPf as catalysts,
this type of aza-Diels–Alder reaction proceeded smoothly
to give the corresponding aza-Diels–Alder adduct 3a in
good yields. KOPf did not efficiently catalyze this reaction
under the same conditions. The results are listed in Table 3
(entries 2–5). The lanthanide triflates such as Sc(OTf)3 or
Yb(OTf)3 and Yb(OPf)3 did not efficiently catalyze this
reaction in scCO2 (9.0 MPa) as those of LiOPf, or NaOPf
(Table 3, entries 6–8), although using Sc(OPf)3 as a catalyst
under higher pressure of scCO2 (10 MPa), this reaction
could proceed smoothly to give the adduct in high yield.17d
LiOPf appeared to be the catalyst of choice in our study.
necessary. All solid compounds reported in this paper
gave satisfactory CHN microanalyses. Reagents obtained
commercially were used without further purification. All
reactions were monitored by TLC with Huanghai GF254
silica gel coated plates. Flash column chromatography was
carried out using 300–400 mesh silica gel at increased
pressure. C8F17SO3H was purchased from TCI (Tokyo
Kasei, H0781).
3.2. General procedure for the Mannich-type reaction of
imine 1 with (1-methoxy-2-methylpropenyloxy)-
trimethylsilane and aza-Diels–Alder reaction of imine 1
with Danishefsky’s diene in the presence of LiOPf in
scCO2
Under the optimized reaction conditions, we then examined
the aza-Diels–Alder reaction of Danishefsky’s diene with
various imines in scCO2. The results are summarized in
Table 4. As can be seen from Table 4, the corresponding
nitrogen-containing six-membered ring compounds 3 can be
obtained in good yields (Table 4, entries 1–5).
Imine 1a (54 mg, 0.30 mmol), (1-methoxy-2-methyl-
propenyloxy) trimethylsilane (90 mL, 0.45 mmol) or
Danishefsky’s diene (90 mL, 0.45 mmol), and LiOPf
(15 mg, 10 mol%) were placed in a stainless high pressure
reaction vessel of scCO2. The reaction was performed at
50 8C, 9 MPa for 10 h under CO2 pressure. After the CO2
pressure was released, the residue was washed with water
and extracted with Et2O. The organic layer was dried over
anhydrous MgSO4. The solvent was removed under reduced
pressure and the residue was purified by passing through a
silica gel column (hexane/ethyl acetate¼1/4 as an eluent) to
afford the products 2a and 3a as oily or solid compound.
Table 4. LiOPf catalyzed-aza-Diels–Alder reaction in scCO2
3.2.1. 2,2-Dimethyl-3-phenyl-3-phenylaminopropionic
acid methyl ester 2a. A white solid, 79 mg, yield 93%;
this is a known compound. Its H NMR spectroscopic data
are in consistent with those reported in literature.25
Entry
Ar
C6H5
p-MeOC6H4
p-NO2C6H4
p-ClC6H4
C6H5
Ar0
Time (h)
3, Yields (%)a
1
1
2
3
4
5
m-CF3C6H4
C6H5
C6H5
C6H5
m-FC6H4
10
10
10
10
10
3b, 72
3c, 75
3d, 80
3e, 84
3f, 70
1H NMR (CDCl3, 300 MHz) d 1.16 (3H, s, CH3), 1.27 (3H,
s, CH3), 3.65 (3H, s, OCH3), 4.49 (1H, s, CH), 4.79 (1H, s,
NH), 6.49 (2H, dd, J¼1.2, 8.7 Hz, ArH), 6.59 (1H, t,
J¼7.5 Hz, ArH), 7.04 (2H, dd, J¼7.5, 8.7 Hz, ArH), 7.17–
7.29 (5H, m, ArH).
LiOPf¼C8F17SO3Li.
a
Isolated yield.
In conclusion, Mannich-type reaction of imines with
(1-methoxy-2-methylpropenyloxy)trimethylsilane and the
aza-Diels–Alder reaction of Danishefsky’s diene with
imines take place in scCO2 in the presence of LiOPf
(C8F17SO3Li) under relatively milder conditions
(9.0 MPa).24 This finding offers an access to the formation
of b-amino carbonyl compounds20 and nitrogen-containing
six-membered ring compounds under environmentally
benign conditions by means of a CO2-philic catalyst
LiOPf (C8F17SO3Li) and the use of hazardous organic
solvents for these reactions can be avoided. Further
investigations to develop other types of reactions in scCO2
or modified scCO2 are now in progress.
3.2.2. 2,2-Dimethyl-3-phenyl-3-(3-trifluoromethylphenyl-
amino)propionic acidmethylester 2b. A whitesolid, 89 mg,
yield 85%. Mp 108–110 8C; IR (CHCl3) n 1714, 1616, 1519,
;
1495, 1437, 1266, 1124, 785 cm21 1H NMR (CDCl3,
300 MHz) d 1.17 (3H, s, CH3), 1.30 (3H, s, CH3), 3.66 (3H,
s, OCH3), 4.46 (1H, s, CH), 5.14 (1H, s, NH), 6.60 (1H, d,
J¼8.1 Hz, ArH), 6.72 (1H, s, ArH), 6.82 (1H, d, J¼8.1 Hz,
ArH), 7.11 (1H, t, J¼8.1 Hz, ArH), 7.21–7.33 (5H, m, ArH);
13C NMR (CDCl3, 75 MHz) d 21.1, 25.0, 47.1, 52.4, 64.7,
110.0 (q, J¼4.1 Hz), 114.1 (q, J¼4.2 Hz), 116.2, 117.7 (q,
J¼277.5 Hz), 127.9, 128.4, 128.5, 129.7, 129.9 (q,
J¼10.1 Hz), 138.7, 147.3, 177.1; MS (EI) m/z 351 (Mþ,
2.16), 250 (Mþ2101, 100), 172 (Mþ2179, 11.97), 145
(Mþ2206, 15.63). Anal. calcd for C19H20F3NO2 requires C,
64.95; H, 5.74; N, 3.99. Found: C, 65.06; H, 5.88; N, 3.95%.
3. Experimental
3.2.3. 2,2-Dimethyl-3-(4-methoxyphenyl)-3-phenyl-
aminopropionic acid methyl ester 2c. A yellowish oil,
61 mg, yield 66%; IR (CHCl3) n 1727, 1603, 1510, 1265,
1178, 1034 cm21; 1H NMR (CDCl3, 300 MHz) d 1.15 (3H,
s, CH3), 1.25 (3H, s, CH3), 3.65 (3H, s, OCH3), 3.76 (3H, s,
OCH3), 4.44 (1H, s, CH), 4.74 (1H, s, NH), 6.49 (2H, d,
J¼8.4 Hz, ArH), 6.59 (1H, t, J¼7.4 Hz, ArH), 6.81 (2H, d,
J¼8.7 Hz, ArH), 7.04 (2H, dd, J¼7.4 Hz, 8.4 Hz, ArH),
3.1. General methods
Melting points are uncorrected. H and 13C NMR spectra
1
were recorded at 300 and 75 MHz, respectively, with
tetramethylsilane (TMS) as an internal standard. Mass
spectra were recorded by EI methods, and HRMS was
measured on a Finnigan MAþ mass spectrometer. Organic
solvents used were dried by standard methods when

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M. Shi et al. / Tetrahedron 60 (2004) 6163–6167
7.18 (2H, d, J¼8.7 Hz, ArH); 13C NMR (CDCl3, 75 MHz) d
20.9, 24.7, 47.4, 52.3, 55.4, 64.0, 113.6, 113.7, 117.4, 129.2,
129.5, 131.4, 147.2, 159.1, 177.3; MS (EI) m/z 313 (Mþ,
3.08), 212 (Mþ2101, 100), 168 (Mþ2145, 6.10), 104
(Mþ2209, 15.95), 77(Mþ2236, 14.87); HRMS (MALDI)
calcd for C19H24O3N (MþþH) requires 314.1756. Found:
314.1751.
5.31 (2H, m, CH2), 7.00–7.05 (2H, m, ArH), 7.08–7.14
(1H, m, ArH), 7.25–7.33 (7H, m, ArH), 7.68 (1H, dd,
J¼1.2, 7.8 Hz, CH).
3.2.8. 2-Phenyl-1-(3-trifluoromethylphenyl)-2,3-di-
hydro-1H-pyridin-4-one 3b. A colorless oil (68 mg,
;
72%); IR (CHCl3) n 1653, 1589, 1497, 1336 cm21 1H
NMR (CDCl3, 300 MHz) d 2.84 (1H, ddd, J¼1.3, 3.3,
16.5 Hz, CH), 3.30 (1H, dd, J¼7.0, 16.4 Hz, CH), 5.28–
5.31 (1H, m, CH2), 5.36 (1H, dd, J¼0.8, 8.0 Hz, CH2),
7.13–7.41 (9H, m, ArH), 7.67 (1H, dd, J¼0.8, 7.9 Hz, CH);
13C NMR (CDCl3, 75 MHz) d 43.5, 61.7, 104.3, 115.1 (q,
J¼3.9 Hz), 120.7 (q, J¼3.9 Hz), 121.3, 123.5 (q, J¼
271.3 Hz), 126.0, 128.1, 129.1, 129.1, 130.2, 131.9 (q,
J¼33.9 Hz), 137.2, 145.0, 147.3, 190.2; MS (EI) m/z 317
(Mþ, 84.57), 240 (Mþ277, 95.26), 185 (Mþ2132, 100), 77
(Mþ2240, 6.25); HRMS (MALDI) calcd for C18H15OF3N
(MþþH) requires 318.1106. Found: 318.1100.
3.2.4. 2,2-Dimethyl-3-(4-nitrophenyl)-3-phenylamino-
propionic acid methyl ester 2d. A yellow solid, 81 mg,
yield 83%; mp 103–105 8C; IR (CHCl3) n 1728, 1603,
1507, 1523, 1438, 1266, 1139, 853 cm21; 1H NMR (CDCl3,
300 MHz) d 1.18 (3H, s, CH3), 1.32 (3H, s, CH3), 3.67 (3H,
s, OCH3), 4.57 (1H, d, J¼7.1 Hz, CH), 4.90 (1H, d,
J¼7.1 Hz, NH), 6.45 (2H, d, J¼8.6 Hz, ArH), 6.64 (1H, t,
J¼7.5 Hz, ArH), 7.06 (2H, dd, J¼7.5 Hz, 8.6 Hz, ArH),
7.49 (2H, d, J¼8.9 Hz, ArH), 8.16 (2H, d, J¼8.9 Hz, ArH);
13C NMR (CDCl3, 75 MHz) d 21.1, 24.5, 46.8, 52.3, 64.2,
113.3, 118.0, 123.3, 129.1, 129.2, 146.1, 147.4, 147.5,
176.2; MS (EI) m/z 328 (Mþ, 5.74), 227 (Mþ2101, 100),
181 (Mþ2147, 37.21), 168 (Mþ2160, 8.99), 77 (Mþ2251,
19.42). Anal. calcd for C18H20N2O4 requires C, 65.84; H,
6.14. N, 8.53. Found: C, 65.99; H, 6.14; N, 8.44%.
3.2.9. 2-(4-Methoxyphenyl)-1-phenyl-2,3-dihydro-1H-
pyridin-4-one 3c. A yellowish oil (63 mg, 75%); this is a
1
known compound. Its H NMR spectroscopic data are in
consistent with those reported in the literature.23 1H NMR
(CDCl3, 300 MHz) d 2.76 (1H, ddd, J¼1.0, 3.3, 16.3 Hz,
CH), 3.26 (1H, dd, J¼6.9, 16.3 Hz, CH), 3.78 (3H, s,
OCH3), 5.24 (1H, dd, J¼3.3, 7.1 Hz, CH2), 5.28 (1H, dd,
J¼1.0, 7.1 Hz, CH2), 6.84 (2H, d, J¼2.1, 6.6 Hz, ArH),
7.01–7.33 (7H, m, ArH), 7.64 (1H, dd, J¼1.0, 7.8 Hz, CH).
3.2.5. 2,2-Dimethyl-3-(4-chlorophenyl)-3-phenylamino-
propionic acid methyl ester 2e. A white solid, 54 mg,
yield 60%; mp 108–110 8C; IR (CHCl3) n 1732, 1613,
;
1510, 1533, 1442, 1149, 873 cm21 1H NMR (CDCl3,
300 MHz) d 1.15 (3H, s, CH3), 1.27 (3H, s, CH3), 3.65 (3H,
s, OCH3), 4.45 (1H, s, CH), 4.79 (1H, s, NH), 6.46 (2H, dd,
J¼1.0, 8.8 Hz, ArH), 6.62 (1H, t, J¼7.4 Hz, ArH), 7.05 (2H,
dd, J¼7.4, 8.8 Hz, ArH), 7.20–7.28 (4H, m, ArH); 13C
NMR (CDCl3, 75 MHz) d 20.8, 24.4, 46.9, 52.1, 65.8,
113.3, 117.5, 128.2, 129.0, 129.6, 133.2, 137.9, 146.6,
176.7; MS (EI) m/z 317 (Mþ, 4.63), 216 (Mþ2101, 100),
180 (Mþ2137, 4.27), 104 (Mþ2213, 13.22), 77 (Mþ2240,
19.37). Anal. calcd for C18H20ClNO2 requires C, 68.03; H,
6.34; N, 4.41. Found: C, 68.26; H, 6.33; N, 4.40%.
3.2.10. 2-(4-Nitrophenyl)-1-phenyl-2,3-dihydro-1H-pyri-
din-4-one 3d. A yellow solid (71 mg, 80%); this is a known
compound. Its 1H NMR spectroscopic data are in consistent
with those reported in the literature.23 1H NMR (CDCl3,
300 MHz) d 2.78 (1H, dd, J¼2.9, 16.2 Hz, CH), 3.37 (1H,
dd, J¼7.3, 16.2 Hz, CH), 5.34 (1H, d, J¼7.9 Hz, CH2), 5.39
(1H, dd, J¼2.8, 7.9 Hz, CH2), 6.99 (2H, d, J¼7.8 Hz, ArH),
7.15 (1H, t, J¼7.4 Hz, ArH), 7.33 (2H, dd, J¼7.4, 7.8 Hz,
ArH), 7.47 (2H, d, J¼8.5 Hz, ArH), 7.70 (1H, d, J¼7.7 Hz,
CH), 8.21 (2H, d, J¼8.5 Hz, ArH); MS (EI) m/z 294 (Mþ,
100), 172 (Mþ2122, 29.9), 145 (Mþ2149, 81.07), 117
(Mþ2177, 67.36), 77 (Mþ2217, 25.47).
3.2.6. 2,2-Dimethyl-3-phenyl-3-(3-fluorophenylamino)-
propionic acid methyl ester 2f. A white solid (47 mg,
52%); mp 89–91 8C; IR (CHCl3) n 1727, 1591, 1493, 1265,
1
1150 cm21; H NMR (CDCl3, 300 MHz) d 1.15 (3H, s,
3.2.11. 2-(4-Chlorophenyl)-1-phenyl-2,3-dihydro-1H-
pyridin-4-one 3e. A white solid (72 mg, 84%); this is a
CH3), 1.28 (3H, s, CH3), 3.66 (3H, s, OCH3), 4.41 (1H, d,
J¼7.3 Hz, CH), 5.02 (1H, d, J¼7.3 Hz, NH), 6.15 (1H, dt,
J¼2.8 Hz, 11.8 Hz, ArH), 6.25–6.31 (2H, m, ArH), 6.96
(1H, dd, J¼8.1 Hz, 15.0 Hz, ArH), 7.23–7.29 (5H, m,
ArH); 13C NMR (CDCl3, 75 MHz) d 21.1, 24.9, 47.1, 52.3,
64.8, 100.3 (d, J¼25.5 Hz), 104.0 (d, J¼22.1 Hz), 109.5 (d,
J¼2.4 Hz), 127.9, 128.4 (d, J¼3.6 Hz), 130.2, 130.3, 139.0,
149.0 (d, J¼11.0 Hz), 164.1 (d, J¼254.7 Hz), 177.1; MS
(EI) m/z 301 (Mþ, 3.40), 200 (Mþ2101, 100), 122
(Mþ2179, 21.75), 95 (Mþ2206, 20.93), 77 (Mþ2224,
9.22). Anal. calcd for C18H20FNO2 requires C, 71.74; H,
6.69; N, 4.65. Found: C, 71.80; H, 6.40; N, 4.53%.
1
known compound. Its H NMR spectroscopic data are in
consistent with those reported in the literature.23 1H NMR
(CDCl3, 300 MHz) d 2.75 (1H, ddd, J¼1.0, 3.4, 16.5 Hz,
CH), 3.30 (1H, dd, J¼6.9, 16.5 Hz, CH), 5.26 (1H, dd,
J¼3.3, 7.6 Hz, CH2), 5.29 (1H, dd, J¼1.2, 9.1 Hz, CH2),
7.00 (2H, d, J¼7.7 Hz, ArH), 7.10–7.34 (7H, m, ArH), 7.65
(1H, dd, J¼1.0, 7.6 Hz, CH); MS (EI) m/z 283 (Mþ, 98.03),
172 (Mþ2111, 100), 145 (Mþ2138, 95.68), 117
(Mþ2166, 81.18), 77 (Mþ2206, 33.47).
3.2.12. 1-(3-Fluorophenyl)-2-phenyl-2,3-dihydro-1H-
pyridin-4-one 3f. A colorless oil (55 mg, 70%). IR
;
(CHCl3) n 1653, 1591, 1494, 1366 cm21 1H NMR
(CDCl3, 300 MHz) d 2.81 (1H, ddd, J¼1.1 Hz, 2.9 Hz,
16.4 Hz, CH), 3.31 (1H, dd, J¼6.9, 16.4 Hz, CH), 5.27 (1H,
dd, J¼2.6, 7.1 Hz, CH2), 5.32 (1H, dd, J¼0.8, 7.1 Hz, CH2),
6.70–6.75 (1H, m, ArH), 6.78–6.82 (2H, m, ArH), 7.20–
7.35 (6H, m, ArH), 7.66 (1H, dd, J¼1.1, 7.9 Hz, CH); 13C
NMR (CDCl3, 75 MHz) d 43.4, 61.5, 103.6, 105.6 (d,
3.2.7. 1,2-Diphenyl-2,3-dihydro-1H-pyridin-4-one 3a. A
white solid (66 mg, 88%); this is a known compound. Its 1H
NMR spectroscopic data are in consistent with those
reported in literature.26
1H NMR (CDCl3, 300 MHz) d 2.79 (1H, ddd, J¼1.2, 3.3,
16.4 Hz, CH), 3.31 (1H, dd, J¼6.6, 16.4 Hz, CH), 5.26–

M. Shi et al. / Tetrahedron 60 (2004) 6163–6167
6167
14. Hadida, S.; Super, M. S.; Beckman, E. J.; Curran, D. P. J. Am.
Chem. Soc. 1997, 119, 7406–7407.
J¼21.2 Hz), 110.9 (d, J¼21.2 Hz), 113.6 (d, J¼3.4 Hz),
125.9, 127.9, 130.8 (d, J¼9.5 Hz), 137.3, 146.1 (d,
J¼10.0 Hz), 147.3, 163.2 (d, J¼256.4 Hz),190.2; MS (EI)
m/z 267 (Mþ, 65.81), 190 (Mþ277, 49.22), 163 (Mþ2104,
52.31), 135 (Mþ2132, 100), 95 (Mþ2172, 52.69); HRMS
(MALDI) calcd for C17H15OFN (MþþH) requires
268.1138. found: 268.1132.
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Acknowledgements
We thank the State Key Project of Basic Research (Project
973) (No. G2000048007), Shanghai Municipal Committee
of Science and Technology, and the National Natural
Science Foundation of China (20025206, 203900502, and
20272069) for financial supports.
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